Ages And Metallicities For Stars In The Galactic Bulge

Abstract

Observations of the stellar content of the Milky Way's bulge helps to understand the stellar content and evolution of distant galaxies. In this brief overview I will first highlight some recent work directed towards measuring the history of star formation and the chemical composition of the central few parsecs of the Galaxy. High resolution spectroscopic observations by Ramrez et al. (1998) of luminous M stars in this region yield a near solar value for [Fe/H] from direct measurements of iron lines. Then I will present some results from an ongoing program by my colleagues and myself which has the objective of delineating the star formation and chemical enrichment histories of the central 100 parsecs of the Galaxy, the ``inner bulge''. We have found a small increase in mean [Fe/H] from Baade's Window to the Galactic Center and deduce a near solar value for stars at the center. For radial distances greater than one degree we fail to find a measurable population of stars that are significantly younger than those in Baade's Window. Within one degree of the Galactic Center we find a number of luminous M giants that most likely are the result of a star formation episode not more than one or two Gyr ago.